Negative transcriptional regulation of human colonic smooth muscle Ca v1.2 channels by p50 and p65 subunits of nuclear factor-κB

Xuan-Zheng Shi, Konrad Pazdrak, Nehad Saada, Bosong Dai, Philip Palade, Sushil K. Sarna

Research output: Contribution to journalArticle

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Abstract

Background & Aims: The expression of Cav1.2 channels in colonic circular smooth muscle cells and the contractility of these cells are suppressed in inflammation. Our aim was to investigate whether the activation of p50 and p65 nuclear factor-κB subunits mediates these effects. Methods: Primary cultures of human colonic circular smooth muscle cells and muscle strips were used. Results: The messenger RNA and protein expression of the pore-forming α1C subunit of Cav1.2 channels decreased time dependently in response to tumor necrosis factor α. This effect was blocked by prior transient transfection of the cells with antisense oligonucleotides to p50 or p65. The overexpression of p50 and p65 inhibited the constitutive expression of α1C. Three putative κB binding motifs were identified on the 5′ flanking region of exon 1b of the human L-type calcium channel α1C gene. Progressive 5′ deletions of the promoter and point mutations of the κB binding motifs indicated that the two 5′ binding sites, but not the third 3′ binding site, were essential for the suppression of α1C. Transient transfection of human colonic circular muscle strips with antisense oligonucleotides to p50 and p65 decreased expression of the 2 nuclear factor-κB units and reversed the suppression of α1C, as well as that of the contractile response to acetylcholine, by 24 hours of treatment with tumor necrosis factor α. Conclusions: The activation of p50 and p65 by tumor necrosis factor α suppresses the expression of the α1C subunit of Cav1.2 channels in human colonic circular smooth muscle cells and their contractile response to acetylcholine. Nuclear factor-κB must bind concurrently to the two 5′ κB motifs on the promoter of α1C to produce this effect.

Original languageEnglish (US)
Pages (from-to)1518-1532
Number of pages15
JournalGastroenterology
Volume129
Issue number5
DOIs
StatePublished - Nov 2005

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Smooth Muscle
Smooth Muscle Myocytes
Tumor Necrosis Factor-alpha
Antisense Oligonucleotides
Acetylcholine
Transfection
Binding Sites
L-Type Calcium Channels
Muscles
Porins
Sequence Deletion
5' Flanking Region
Point Mutation
Exons
Inflammation
Messenger RNA
Genes

ASJC Scopus subject areas

  • Gastroenterology

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Negative transcriptional regulation of human colonic smooth muscle Ca v1.2 channels by p50 and p65 subunits of nuclear factor-κB. / Shi, Xuan-Zheng; Pazdrak, Konrad; Saada, Nehad; Dai, Bosong; Palade, Philip; Sarna, Sushil K.

In: Gastroenterology, Vol. 129, No. 5, 11.2005, p. 1518-1532.

Research output: Contribution to journalArticle

Shi, Xuan-Zheng ; Pazdrak, Konrad ; Saada, Nehad ; Dai, Bosong ; Palade, Philip ; Sarna, Sushil K. / Negative transcriptional regulation of human colonic smooth muscle Ca v1.2 channels by p50 and p65 subunits of nuclear factor-κB. In: Gastroenterology. 2005 ; Vol. 129, No. 5. pp. 1518-1532.
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abstract = "Background & Aims: The expression of Cav1.2 channels in colonic circular smooth muscle cells and the contractility of these cells are suppressed in inflammation. Our aim was to investigate whether the activation of p50 and p65 nuclear factor-κB subunits mediates these effects. Methods: Primary cultures of human colonic circular smooth muscle cells and muscle strips were used. Results: The messenger RNA and protein expression of the pore-forming α1C subunit of Cav1.2 channels decreased time dependently in response to tumor necrosis factor α. This effect was blocked by prior transient transfection of the cells with antisense oligonucleotides to p50 or p65. The overexpression of p50 and p65 inhibited the constitutive expression of α1C. Three putative κB binding motifs were identified on the 5′ flanking region of exon 1b of the human L-type calcium channel α1C gene. Progressive 5′ deletions of the promoter and point mutations of the κB binding motifs indicated that the two 5′ binding sites, but not the third 3′ binding site, were essential for the suppression of α1C. Transient transfection of human colonic circular muscle strips with antisense oligonucleotides to p50 and p65 decreased expression of the 2 nuclear factor-κB units and reversed the suppression of α1C, as well as that of the contractile response to acetylcholine, by 24 hours of treatment with tumor necrosis factor α. Conclusions: The activation of p50 and p65 by tumor necrosis factor α suppresses the expression of the α1C subunit of Cav1.2 channels in human colonic circular smooth muscle cells and their contractile response to acetylcholine. Nuclear factor-κB must bind concurrently to the two 5′ κB motifs on the promoter of α1C to produce this effect.",
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AU - Dai, Bosong

AU - Palade, Philip

AU - Sarna, Sushil K.

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N2 - Background & Aims: The expression of Cav1.2 channels in colonic circular smooth muscle cells and the contractility of these cells are suppressed in inflammation. Our aim was to investigate whether the activation of p50 and p65 nuclear factor-κB subunits mediates these effects. Methods: Primary cultures of human colonic circular smooth muscle cells and muscle strips were used. Results: The messenger RNA and protein expression of the pore-forming α1C subunit of Cav1.2 channels decreased time dependently in response to tumor necrosis factor α. This effect was blocked by prior transient transfection of the cells with antisense oligonucleotides to p50 or p65. The overexpression of p50 and p65 inhibited the constitutive expression of α1C. Three putative κB binding motifs were identified on the 5′ flanking region of exon 1b of the human L-type calcium channel α1C gene. Progressive 5′ deletions of the promoter and point mutations of the κB binding motifs indicated that the two 5′ binding sites, but not the third 3′ binding site, were essential for the suppression of α1C. Transient transfection of human colonic circular muscle strips with antisense oligonucleotides to p50 and p65 decreased expression of the 2 nuclear factor-κB units and reversed the suppression of α1C, as well as that of the contractile response to acetylcholine, by 24 hours of treatment with tumor necrosis factor α. Conclusions: The activation of p50 and p65 by tumor necrosis factor α suppresses the expression of the α1C subunit of Cav1.2 channels in human colonic circular smooth muscle cells and their contractile response to acetylcholine. Nuclear factor-κB must bind concurrently to the two 5′ κB motifs on the promoter of α1C to produce this effect.

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